Abstract: The outer Milky Way halo is extremely dark matter dominated, and its stellar content is made up of accreted substructures that did not form in our Galaxy. Finding and characterizing these substructures, particularly ultra-faint dwarf galaxies and stellar streams, provides a unique probe of the nature and distribution of dark matter in the Milky Way. These efforts have been enabled by wide field photometric surveys such as the Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey (DES). To continue to make progress in these efforts with current and upcoming surveys it is important to calibrate the data products precisely and understand the various survey selection functions. In this talk, I will discuss how we can learn about the nature of dark matter by studying the Milky Way halo substructures. Then I will share some of our efforts to find and characterize these substructures, focusing on stellar streams, with current surveys like the DECam Local Volume Exploration Survey (DELVE). Finally, I will discuss the current status of the Vera C. Rubin observatory and our efforts to ensure future discoveries with the Legacy Survey of Space and Time (LSST) through careful verification and validation of the survey data.